[Dad's72]

Hey y’all. I have hit 45K miles on my 2015 Chevy Silverado LTZ 5.3L. It is time to do the scheduled automatic transmission fluid/filter change. I talked to the dealership because this is the newest vehicle I have ever owned. They said they would give me a $10 discount and do it for $229.00. I asked if they flushed the fluid and they said that has proven to cause damage so all they do is drop the pan, change the filter, and top off. I figure if that is all they do then I can do that.
My question to y’all that have done this on these trucks before is this, is it possible to do with the exhaust in the way? I saw a guy use a jack and pry a piece of metal to move the exhaust down enough to get the pan out. Do y’all think that could ruin the seal between the manifold and exhaust pipes?
Next question: I changed the fluid in an older highlander and I attached a long piece of hose to the cooler line and started the car up. This pushed out more than half the fluid. Do y’all think that hurts the transmission?

Thanks. Open to suggestions. Trying to do it this weekend in the driveway. I need to find out which filter and what fluid I will need. Thinking about getting the stuff from the dealership.